Irrigation
BASICS
Irrigation systems should have head-to-head coverage. If you are getting quotes make sure to get all contractors to quote this type of spacing. If you get a low bid that seems out of place be sure to ask questions, you get what you pay for. Once your system is installed the first thing you need to do is measure how long it takes each zone to deliver ½ inch of water. The best way to do this is get several rain gauges and strategically place them throughout each zone as you measure. Once you know how long it takes to irrigate ½ inch write it down in your controller box next to each station. Remember that there are limitless combinations of sprinkler head size and nozzle size pairings that can be used in a single system. It is very unlikely that each zone will take the same amount of time to put out ½ inch of water. Think of irrigating in inches not minutes.
If you don’t have an irrigation system, don’t despair. Your disease pressure will be far less than that of your neighbor who does have one and is constantly over watering. Just move your hoses around the yard and keep watering the dry spots. When folks call us with disease issues one of the first questions we ask “tell me about your irrigation practices”. Then we get responses like “fifteen minutes every other day” which tells us they are keeping just the top of the soil very wet, bad news. Or some respond with “oh water is not the problem, we water from 45 minutes to an hour every day”, even worse. Irrigation is to supplement rain fall and perhaps in a drought replace it. Have you ever lived anywhere it rained 15 minutes every other day or 45 minutes to an hour every day? Water in inches, when the grass is dry.
FREQUENCY
The number one cause of death to house plants is over watering. Keep this in mind when it comes to your thought process regarding how you plan to irrigate. One of the worst things you can do to any grass is over water. Remember that roots need oxygen to survive and if you irrigate too much or too frequently you will eventually cause the roots to ferment and rot. For established lawns one inch a week should do unless your soil is very sandy or you are in a drought. Our recommendation is to water heavily once a week but only as needed. That is to say if it rains heavily within that week don’t irrigate! Watch out for those irrigation controllers. They are not rotisserie cookers; you can’t “set it and forget it”! It’s okay for grass to dry out. If you come home and notice that your lawn is dry, set the system to run the next morning. Then turn it off and wait until it gets dry again.
TIMING
Early morning is by far the best time to irrigate. Set your system to run as the sun is coming up and finish by mid morning. This will give the wind and sun plenty of time to dry the plant and surface of the ground before the sun sets. When grass plants stay saturated during the night time hours the turfgrass environment becomes a breeding ground and buffet for a slew of diseases. You must resist the urge to water when you get home from a long day at work and feel like your grass needs water. It probably does need water, but wait until the morning to start your irrigation cycle.
NEW SOD IN THE SUMMER
Newly laid sod cannot be over watered in the first few days. The rule of thumb for irrigating new sod is to get it so wet that you cannot walk on it without causing damage. Another way to tell you have put enough water down initially is to pull back a piece of sod and stick a screwdriver into the ground. Wiggle the screwdriver to make a hole a couple times larger than the diameter of the screwdriver. Remove the screwdriver and if the hole does not almost instantly fill with water – water some more. Once the sod and the ground are completely saturated you should water 2-3 times a day for the next seven to ten days depending on soil type and time of year. Those subsequent irrigation cycles should be early in the morning through early to mid afternoon. Under no circumstances should you water into the evening or through the night. This is a sure way to invite disease into your new grass. In week two you should cut back to one good soaking a day always being sure to monitor that the grass is getting all it needs. By week three roots should be developing and you should be able to cut back to every other day. By week four you should be able to cut back to every 3 to 4 days.
NEW SOD IN THE WINTER
We sell a lot of sod in the winter. The popular misconception is that winter sod will succumb to the cold and die in the winter. In fact winter sod does quite well unless it isn’t irrigated. Sod is far more likely to die from drought in the winter than cold. The newly laid sod sits on top of the ground and has no roots (we kept them here at the farm). As the sun hits it and wind blows across the sod it can and will dry out unless watered. The rule of thumb for irrigating winter sod is to be sure that it gets water once a week. Don’t leave the irrigation system set for once a week. Just water it if it has not rained in the past week.
SUMMARY
Water is a precious resource and believe it or not wars will be waged over water rights in the future. We need to be judicious in our use of water or face loosing the privilege of having healthy irrigated lawns. Just as we become better at recycling and searching for alternative energy sources we must be stewards of our limited water resources.
